South African authorities are attempting to limit inflows of illegal immigrants. Evidence for the United States presented in Dixon et al (2011) suggests that a policy-induced reduction in labour supply from illegal immigrants generates a welfare loss for legal residents. I use a similar labour market mechanism within a dynamic CGE model for South Africa, but take into consideration a number of well-known facts about the local economy. With high unemployment rates among low skilled workers and a legal minimum wage in place, I find a net gain in employment and welfare for legal residents in South Africa when reducing the inflow of illegal immigrants.